An uncharacteristically emotional Nancy Pelosi is warning Republicans — and other groups getting whipped up over the health care debate — not to incite unstable supporters who might repeat acts of violence that struck San Francisco in the 1970s.

A top Pelosi aide later confirmed reporters' suggestions that her statement was a reference to the City Hall murder of gay rights activist Harvey Milk and Mayor George Moscone in November 1978 — an earth-shattering experience for Bay Area Democrats like the speaker.

Pelosi stumbled when asked about Rep. Joe Wilson's "You lie!" outburst and its impact on civility in the House, momentarily overcome by emotion.

"I think we all have to take action and responsibility for our words — we are a free country and this balance between freedom and safety is one that we, um, have to carefully balance," said Pelosi, who made no direct mention of Republicans.

A House leadership aide later told me that Democrats have become increasingly concerned by the ratcheting up of rhetoric on both sides — and particularly alarmed by the recent hanging in effigy of Rep. Frank Kratovil (D-Md.) by a tea party activist on the Eastern Shore.

"I have concerns about some of the language that is being used because I saw this myself in the late '70s in San Francisco, this king of rhetoric. ... It created a climate in which violence took place. ... I wish we would all curb our enthusiasm in some of the statements and understand that some of the ears that it is falling on are not as balanced as the person making the statements may assume."

Pelosi, according to her spokesman, Nadeam Elshami, was referring to Supervisor Dan White's murder of Milk and Moscone, the basis for last year's film "Milk."

She added: "You have to take responsibility for any incitement that [the speaker's words] may cause."

The speaker, who served as California state party chairwoman before being elected to the House, was a gay rights advocate who attended Milk's funeral.

Ironically, the most notorious act of violence to afflict the health care debate was the recent scrum between a pro-reform protester and a tea party activist in which the liberal bit off part of the conservative's finger after being punched in the face.

The Pelosi scrap mirrors an earlier fight. In April, the Department of Homeland Security set off a firestorm of protest when it acknowledged it had produced a report titled: "Right-Wing Extremism: Current Economic and Political Climate Fueling Resurgence in Radicalization and Recruitment," which warned that right-wing groups could be spurred to violence by the election of the nation's first African-American president.

Republicans — still upset at Pelosi's charge that disruptions by town hall protesters were "un-American" — were quick to take issue.

National Republican Congressional Committee Chairman Pete Sessions (R-Texas) is the first House GOPer to take issue with Pelosi's contention that the vehemence of anti-health care reform rhetoric could lead to a wave of violence akin to that which hit San Francisco in the '70s:

“Speaker Pelosi is right that the American people are upset, but it is her own words that continue to fuel voter frustration in America," Sessions said in a statement sent to POLITICO. "No longer content with criticizing concerned citizens for being ‘un-American,’ the Speaker is now likening genuine opposition to assassination. Such insulting rhetoric not only undermines the credibility of her office, but it underscores the desperate attempt by her party to divert attention away from a failing agenda."

Sessions, who raised eyebrows earlier this year by suggesting the House GOP minority needed to adapt the insurgent politics of the Taliban, added: "During one of the most important policy debates of our time, the American people have been completely abandoned by those elected representatives under her control. Voters are justifiably frustrated with Washington, and the Speaker's verbal assault on voters accomplishes nothing other than furthering her reputation for being wildly out of touch with the American people.”